Bifunctional Electron-Transporting Agent for Red Colloidal Quantum Dot Light-Emitting Diodes

Ya Kun Wang, Haoyue Wan, Jian Xu, Yun Zhong, Eui Dae Jung, So Min Park, Sam Teale, Muhammad Imran, You Jun Yu, Pan Xia, Yu Ho Won, Kwang Hee Kim, Zheng Hong Lu, Liang Sheng Liao, Sjoerd Hoogland, Edward H. Sargent*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Indium phosphide (InP) quantum dots have enabled light-emitting diodes (LEDs) that are heavy-metal-free, narrow in emission linewidth, and physically flexible. However, ZnO/ZnMgO, the electron-transporting layer (ETL) in high-performance red InP/ZnSe/ZnS LEDs, suffers from high defect densities, quenches luminescence when deposited on InP, and induces performance degradation that arises due to trap migration from the ETL to the InP emitting layer. We posited that the formation of Zn2+ traps on the outer ZnS shell, combined with sulfur and oxygen vacancy migration between ZnO/ZnMgO and InP, may account for this issue. We synthesized therefore a bifunctional ETL (CNT2T, 3′,3′″,3′″″-(1,3,5-triazine-2,4,6-triyl)tris(([1,1′-biphenyl]-3-carbonitrile)) designed to passivate Zn2+ traps locally and in situ and to prevent vacancy migration between layers: the backbone of the small molecule ETL contains a triazine electron-withdrawing unit to ensure sufficient electron mobility (6 × 10-4 cm2 V-1 s-1), and the star-shaped structure with multiple cyano groups provides effective passivation of the ZnS surface. We report as a result red InP LEDs having an EQE of 15% and a luminance of over 12,000 cd m-2; this represents a record among organic-ETL-based red InP LEDs.

Original languageEnglish (US)
Pages (from-to)6428-6433
Number of pages6
JournalJournal of the American Chemical Society
Issue number11
StatePublished - Mar 22 2023

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry


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